Comment by tczMUFlmoNk

I might guess that GP is referring not to interface ergonomics (for which a struct is a perfectly satisfactory solution, as you describe), but to implementation efficiency. A pointer is one word. A slice / string view is two words: a length and a pointer. A pointer to a slice is one word, but requires an additional indirection. I personally agree that slices are probably the best all-around choice, but taking double the memory (and incurring double the register pressure, etc.) is a trade-off that's fair to mention.